Viewing and configuration is done through the iOS app. So to do that, I think that would require Withings to release a Mac app for the baby monitor. As far as I know, they haven't done so. This means you are limited to iOS (and I guess Android?) devices.

I've successfully checked in on my baby in California while on a business trip in Florida. As long as your device has relatively open access to the public internet (and the baby monitor does, too) you should be okay. This worked on hotel WiFi as well as 3G.

It doesn't make for a good videoconferencing solution as there is a lag of a couple seconds between the app recording your voice and when you hear it come out of the baby monitor. But you can say a few things, maybe even sing a song or read a story - as long as it's not too interactive.

Yes. You can have as many Smart Baby Monitor as you want, connected to as many iPhone/iPad as you own. To answer your question, Mom and Dad can access the feed from their own iPhone and connect using a shared iPad as well.

It detects motion in the video signal above a certain threshold and noise in the audio signal above a certain threshold. Anything more than that would have to be interpreted by a person watching the monitor. Depending on the room, angle and placement you might be able to see your baby breathing.

The power connector is a micro USB, so I think it's a matter of getting the right power adapter. The one sold in your area should come with the right adapter. If not, any universal plug adapter should work. (Haven't tried powering mine off a USB hub yet)

The security of this device depends on a number of things, most importantly the strength of the security of your network, in which case I highly recommend if you don't already, you use WPA2 Personal with a complex password (also referred to as a Pre-Shared Key or PSK) for your wifi. A complex password of 20 characters or more that randomly contains letters, numbers and symbols is a good idea.

Additionally the device itself appears to allow 3 user accounts to access it, you'll want to ensure both the names and the passwords of these are changed from their defaults and reasonably hard to guess. Presumably without these credentials it's a lot harder to view the live feed or listen in on the audio.

Prices are inclusive of VAT (20%) and Insurance Premium Tax (where applicable) but exclusive of delivery charges unless otherwise indicated. The VAT rate for products classified as services under EU VAT law will be 23% as VAT is charged at the rate payable in the country where Apple Distribution International supplies such products, which is the Republic of Ireland. The order form shows you the VAT payable on the Products you select.
Apple Distribution International is regulated by the Central Bank of Ireland and has permission to offer its services in certain EEA countries.
For further information, please see registers.centralbank.ie.